1. Field of the Invention
The present invention relates to a recording apparatus for performing recording by means of a recording head on a recording medium transferred along a conveyance route.
2. Related Background Art
In a conventional recording apparatus such as a printer or the like which transfers a recording paper and records signals thereon, a recording paper sensor has generally been utilized for detecting the presence or absence of the recording paper (sheet) on the passage along which it is conveyed FIG. 2 shows a schematic sectional view illustrating a constitution of a recording block in such a conventional printer. In FIG. 2, a thermal head 31 is provided with a plurality of heating elements each heat-driven in accordance with an image signal, thereby permitting recording on the recording paper such as thermosensitive paper and others. The recording paper is sandwiched between a platen roller 32 and a thermal head 31 and conveyed forwardly as the platen roller 32 is rotated in the direction of an arrow "A". A spring 33 is used to press the thermal head 31 against the platen roller 32. A recording paper sensor 34 for detecting the presence or absence of the recording paper is located along the conveyance route for the recording paper and before the recording position by the thermal head 31. A recording paper guide 35 forms a conveyance route for the recording paper and a part of a frame 38 also forms the conveyance route by opposing the recording paper guide 35. The recording paper is inserted through an inlet 36 into the conveyance route and discharged through an outlet 37 out of the apparatus.
The operation of the conventional recording apparatus as constructed above will be hereinafter explained.
When the commencement of print operation is directed by an external device such as a host computer or the like not shown in the drawing, it is determined in response to a signal from the recording paper sensor 34 whether or not the recording paper is present, before the start of the recording operation. With the recording paper present, the platen roller 32 is rotated in the direction of an arrow "A" and the recording paper begins to be conveyed. Simultaneously with this, the heating elements of the thermal head 31 are driven respectively based on the recording information (image data) transmitted from an external device to effect recording on the recording paper. The recording paper on which the image data were printed as previously described is ejected from the outlet 37 toward the outside. Contrary to this, if it is judged based on the signal from the sensor 34 that the recording paper is not present, the platen roller 32 is not rotated. Instead, it is indicated on a display (not shown) that the recording paper is not present on the conveyance route or that the apparatus is not provided with paper.
As clearly understood from the foregoing in the conventional apparatuses, it is required to provide the recording paper sensor for detecting the presence or absence of the recording paper in the conveyance route upstream of a recording position. Accordingly, it will be necessary to have a space and parts for disposing such a sensor, thus causing the problems indicated below.
(i) There is a limitation completing making the apparatus compact, since a suitable space for mounting the sensor in the conveyance route is required. PA1 (ii) Workability and assembly are complicated because additional procedures for mounting the sensor on the conveyance route are required. PA1 (iii) Cost of the apparatus rises due to the cost of the fittings used for mounting the sensor.